1. Field of the Invention
This invention relates to a closed, patient access system which automatically reseals after administering medication using a standard medical implement that directly connects with the system without the need of any intermediary needles, caps or adaptors. A two-way valve eliminating dead space is used which includes a seal which, upon being compressed by the medical implement, is pierced to open the valve and reseals upon being decompressed, maintaining a fluid tight seal even at high pressures and after repeated uses.
2. Background Discussion
The manipulation of fluids for parenteral administration in hospital and medical settings routinely involves the use of connectors and adaptors for facilitating the movement of fluids between two points. Most fluid connectors and adaptors employ needles to pierce a septum covering sterile tubing or to pierce the septum of a medicament container of fluid. Fluid then passes from the container or fluid filled tubing into a syringe or second set of tubing. These connectors and adaptors often have mechanical or moving parts. Since the ready passage of fluids through the connectors and adaptors is often critical to patient survival, it is imperative that the connectors and adaptors function reliably and repeatedly. Adaptors and connectors that malfunction during use may be life-threatening. The more mechanical or moving parts such as springs and diaphragms, the more likely that they will function improperly. Improper functioning can result in the introduction of air embolisms into a patient. Thus, the fewer the mechanical parts, the more these connectors can be relied on and the better they will be accepted by the medical community.
Many connectors or valves, especially those employing several mechanical components, have a relatively high volume of fluid space within them. This xe2x80x9cdead spacexe2x80x9d within the device prevents accurate introduction of precise fluid volumes and provides an opportunity for contamination upon disconnection of the device. Connectors and adaptors often include valves that permit or interrupt the flow of fluid along the course of fluid travel. Several of those commonly in use employ metal needles to puncture sterile seals. Such connectors are generally designed to accommodate fluid flow in one direction. This means that the fluid line must have connectors and tube aligned in complementary directions. These connectors often require further manipulation if, for example, the valve is inadvertently assembled in a direction that will not facilitate fluid flow. These manipulations increase handling, thereby increasing both the risk of contamination and the amount of time required to establish the fluid connection.
Metal needles employed as part of connector devices increase the risk of puncture wounds to the user. The needles used in these devices often have through-holes placed at the tip of the needle. Connection of the valve with a flow line involves piercing the needle through a sealed septum. Through-holes placed at the needle tip can core the septum and release free particulates into the flow line. Such an event can prove fatal to a patient. Such through-holes may also become clogged easily with material from the septum.
Reusable connectors and adaptors are preferred for medical applications since components must often be added or removed from a fluid line connected to a patient.
Reusable connectors, however, are difficult to keep sterile. Sometimes caps are employed to cover the connector to keep it sterile. Frequently, these caps are lost, or simply not used because they are not readily available when needed.
A closed, patient access system that is easy to use and employs only a valve device in communication with the patient that need not be capped or interconnected with the medical implement through a needle or adaptor, is swabbable, is sufficiently durable to maintain its function after several manipulations, and maintains a fluid-tight seal at high pressures, would be of great benefit to the medical community.
The valve of this invention has several features, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of this invention as expressed by the claims which follow, its more prominent features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled, xe2x80x9cDETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS,xe2x80x9d one will understand how the features of this invention provide its advantages, which include safety, reliable and repeatable performance, elimination of dead space, simplicity of manufacture and use, and employment of a valve that is swabbable after use to provide sterility and has a fluid-tight seal at high pressure.
This invention is a closed, patient access system which automatically reseals after administering medication using a medical implement that directly connects with the system without the need of any intermediate needles, caps or adaptors. A two-way valve is employed utilizing a reusable seal that may be repeatedly pierced by an enclosed, protected, non-metallic spike rather than an exposed metal needle. The valve facilitates fluid, particularly liquid, transfer while maintaining sterility. The valve is easy to use and is capable of locking in place. After use, the valve is swabbed in the conventional manner with a suitable substance to maintain sterility. The design of the valve avoids accidental needle sticks. As will be discussed in detail below, the valve is useful as a medical connector or adaptor to enable liquid flow from a sealed container.
The first feature of this invention is that the valve has a body including wall structure defining an internal cavity having a proximal end and a distal end. The cavity has an open space into which the seal is pushed, and preferably has a plurality of radial indentations in the wall structure that are adjacent the seal to accommodate the expansion of the seal upon compression. The proximal end has an opening sufficiently large to receive a delivery end of a medical implement which transfers fluid through the delivery end. In most applications, the delivery end of the implement is tapered, and the wall structure adjacent the opening is tapered inward so that the wall structure and the tapered delivery end fit snug against each other upon insertion of the delivery end into the opening. The proximal end of the cavity preferably is adapted to fit snug with an ANSI (American National Standards Institute, Washington, D.C.) standard end of the medical implement. Typically, the implement is a syringe, a connector or inlet/outlet of an IV set, or any one of a wide variety of conduits used in medical applications.
The second feature is that the spike has a tip with at least one hole located at or near the tip, and a passageway in communication with the hole that allows fluid to flow through this hole. The spike is seated inside the cavity such that the tip is inward of the proximal end and is enclosed within the cavity. Preferably, the hole is in a side of the spike adjacent the tip and is elongated, having a size of 18 gauge or greater. The tip may be sharp or slightly rounded. More than one hole is desirable for many applications, and three, symmetrically located holes inward of the proximal end are preferred. The spike may include at least one rib which allows air to enter a space between the seal and the spike, thereby facilitating the sealing of the opening when the implement is removed. The spike may have a substantially conical shape, and the seal has a complementarily, substantially conical shaped cavity within it conforming to the shape of the spike. The spike is disposed within this conical cavity and the seal covers the tip. The tip may be imbedded in the proximal end of the seal or withdrawn into the conical cavity. Preferably, the tip of the spike has a plurality of facets which meet within a recess. The preferred spike should be able to penetrate the seal repeatedly without tearing the seal. Rough edges at the tip may present a tear problem. During injection molding of the preferred plastic spike, facets of the tip will abut along a xe2x80x9cparting line,xe2x80x9d and could form a rough edge which may tear the seal. This problem is avoided where the parting line is buried in a recess. Any rough edge at this parting line is disposed within a recess, so the seal material moves over the recess and does not contact the rough edge.
The third feature is that the resilient seal is adapted to be moved into a compressed state upon insertion of the tip of the medical implement into the opening and returns to a decompressed state upon removal of the tip. The seal in the decompressed state has a section which fills essentially completely a portion of the cavity adjacent the opening. The seal section bears against the wall structure near the opening to seal the opening. In the compressed state, the seal section is pushed by the delivery end of the medical implement away from the opening and into the cavity. A fluid tight seal is maintained between the seal section and the wall structure as the seal is moved into the compressed state. The seal section bears against the wall structure as the seal is moved inward into the cavity by the tip of the medical implement. And most importantly, the delivery end and the seal are adapted to engage so that when the tip of the spike pierces the seal there is essentially no dead space between said delivery end and the seal. Consequently, a predetermined dosage amount of medication is transferred in its entirety to the patient using this invention, with none to the prescribed amount being collected in dead space in the valve. The delivery of an exact amount of medication may be critical in some situations when chemotherapeutic agents are being administered or small children are being treated.
A fluid tight seal is maintained over repeated opening and closing of the valve, and the seal has on its external surface a recess which provides an air pocket to facilitate the movement of the seal. Preferably, the seal presents an essentially flush surface with the proximal end of the cavity. In one embodiment, the proximal end of the seal is substantially flat, the seat is made of a material having a hardness of from 30 to 70 Shore units such as, for example, a silicone polymer. The seal may include a cup-like flange adapted to engage the body near the proximal end of the cavity. A preferred embodiment of the seal comprises a series of O-ring elements stacked together and connected to form a unitary structure. The O-ring elements have increasing diameters, with the smallest diameter element being adjacent the proximal end of the cavity. The proximal end of the seal may be precut to form a tiny orifice therein that allows the tip of the spike to pass therethrough easily upon compression of the seal. Preferably, the proximal end of the seal has a truncated conical shaped segment disposed within the cavity. The seal may also have a centrally located, anti-vacuum, saucer like depression therein, which does not interfere with the ability of the exposed, proximal end of the seal being swabbed when desired.
The fourth feature is that the body and spike are two separate components of the valve that are securely attached to each other by assembly of, and interlocking, of the body and spike. The body has a first locking element near the distal end of the cavity, and the spike has a second locking element adapted to interlock with said first locking element upon assembly. The seal has a lip extending beyond the distal end and positioned between the first and second locking elements so that, upon assembly, the lip is compressed between the locking elements to provide an essentially fluid tight seal upon interlocking.
The fifth feature is that the medical valve includes a support member connected to the spike which seals off the distal end of the cavity. The support member may have a Luer-Lock type connector element that enables the valve to be removably attached to, for example, a fluid line connected to a patient. The support member may also be in the form of an adaptor that enables the valve to be removably attached to a fluid dispenser or container. When used to dispense fluids from a container, the spike has a pair of opposed tips, respectively at the distal and proximal ends of the spike. The tip at the distal end of the spike pierces a cover member which seals the container. A radial slit on the adaptor enables it to deform reversibly sufficiently to fit snugly onto said container.
The sixth feature is that the seal has a proximal end including a pressure responsive element disposed on an inner surface of the seal adjacent the opening. The pressure responsive element in the decompressed state closes any orifice in the seal at the proximal end of the seal to provide an essentially fluid-tight seal while in the decompressed state. The pressure responsive element enables the valve to maintain a fluid-tight seal even at very high pressures sometimes experienced in medical applications, particularly when the valve is connected to a patient""s artery. The valve of this invention will remain closed even when the pressure inside the valve is above 6 pounds per square inch (psi), and it can withstand pressures above 30 psi. Typically, the pressure responsive element is a section of the seal having an entryway into a precut orifice. This section has a substantially cylindrical configuration and is surrounded by an annular space which is filled with pressurized fluid. The center of the member and the annular space are coaxial with the entryway to the orifice. The pressurized fluid fills the annular space to apply pressure that compresses the cylindrical section to tightly close the entryway to the orifice. Preferably, the pressure responsive element has an anti-tear element.
In accordance with this invention, a known, prescribed, predetermined amount or dosage of medication may be transferred from the remote source to the patient directly, so that essentially none of said predetermined amount is collected in dead space in the valve. In other words essentially all the prescribed dosage is receive by the patient and not lost in the valve. Thus, this invention also includes a method of transferring fluid from a remote source to a patient. This invention also includes transfer of fluid from the patient to a remote source. This is possible because the valve of this invention provides two-way communication. The fluid is transferred to the patient by applying pressure the fluid as it passes through the implement so that the pressure applied to the fluid is greater than the pressure of fluid in the patient, enabling transfer from the remote source to the patient. To achieve transfer of fluid from the patient to the remote source, the pressure of fluid in the patient is greater than the pressure at the remote source, causing fluid to flow from the patient to the remote source. This invention also includes a method of transferring fluid in a container having an open mouth covered by a cover member which seals the open mouth. The fluid is caused to flow from the container through the passageway by creating a differential in pressure. Preferably, the valve has an adaptor having a radial slit for allowing the adaptor to deform reversibly sufficiently to fit snugly onto said container.